Lubricating oil and lubrication therewith



at ended ea. 13, E

. 2,139,125 roaarca'rmc on. AND LUBRICATION THEREWITH Elmer William Cook, New York, N. Y., assignor to Tide Water Associated Oil Company, Bayonne, N. J., a corporation of Delaware No Drawing. Application August 13, 1937, I Serial No. 158,916

,6 Claims; (Cl. 87-9) This invention relates to lubricants intended for service in the lubrication of internalv combus tion engines. The invention more particularly is concerned with lubricating or motor oils of mineral hydrocarbon origin which are normally corrosive toward bearing metal alloys of the character of cadmium-silver, cadmium-nickel or copper-lead, as-well as those bearing metals of exceptionally high lead content (of the order of lo 75% to 99%) wherein minor proportions of alloying metals impart unusual hardness to the alloy; and has, for an important objective, the inhibition or prevention of deterioration of such bearing metal in service by the corrosive action of i5 the lubricant thereon.

Eirgine bearings comprising or surfaced with cadmium-silver, high-lead or like alloys now are frequently employed in lieu of the more usual Babbitt metal bearings, in' order to cope with extreme service conditions of friction and temperature. These conditions are the consequences of modern developments in internal combustion engines making available high sustained speeds and requiring bearings formed of metals or alloys having greater resistance to wear, and further characterized by higher melting points necessary to prolonged life under the extreme thermal conditions existing during operation of the en.- gine. Temperatures at the bearing surfaces during operation are, or may be, much higher in the a case of engines requiring these new bearings than formerly was the circumstance with engines in which Babbitt metal bearings gave satisfactory service.

Experience with bearings of the character or type exemplified by cadmium-silver, cadmiumnickel, copper-lead and high-lead alloys has demonstrated, however, that their utility is greatly impaired by an extreme susceptibility to rapid deterioration by the corrosive action or effect of many available lubricating oils. Particularly has this effect been noted when the oils are of the character generally regarded as superior lubricants by conventional criteria.

1 1 Little is known concerning the nature of the corrosive action or its causes; but in general it has been observed that motor oils derived from selected crudes predominantly parafiinic in origin, as well as those oils from these or other crudes which have been improved by treatment with selective solvents, exhibit a marked tendency toward corrosion of the hearings in question, although by other tokens the lubricant is of superior quality. Oxidation stability, as indi- 5 catedby sludge or acid formation in convenproportions.

tional tests indicative of the tendency toward deterioration of the oil itself in service, does not appear to have reliable correlation with the tendency of the oil to corrode bearing surfaces. It is possible that thehigh bearing surface tem- 5 'peratures existing under service conditions with the new bearingsmay be a factor in occasioning the observed deleterious effect of motor oils thereupon. It would appear, also, that the problem of bearing corrosion, with which the present 10 invention is particularly concerned, contrasts with problems of lubricant deterioration per se, since oils characterized by long life and good stability in conventional tests may, and frequently do, prove to be the most corrosive in 16 bcaring corrosion tests. No theory in explanation of the observed corrosive action or the prevention thereof, as herein proposed according to the invention, is intended to be relied upon-1' According to the present invention, it has now 20 been found that the corrosive effect of lubricating oils upon bearing surfaces of the character referred to above maybe avoided in novel and effective manner by incorporating with such oils particular compounds having a retarding or in- 26 hibiting effect in respect of such corrosion. More specifically, the invention arises from the discovery that a compound comprising triphenyl arsine sulfide efiects a very beneficial retardation of the corrosive action of internal combustion "engine lubricating oils upon cadmium-silver,

cadmium-nickel, copper-lead, high-lead and like bearing metal alloys. It is, therefore, an important object of the present invention to inhibit or retard the corrosive deterioration of these and like bearing metal alloys in automotive service by providing a lubricant therefor comprising a refined mineral hydrocarbon oil having incorporated therewith triphenyl arsine sulfide in small but effective pro- 40 portion. Likewise, it is an object of the invention to improve, and to prepare improved, motor oils of petroleum origin by incorporating therein triphenyl arsine sulfide in corrosion inhibiting The provision of an inhibitor ef- 45 fective for such purpose' and comprising a compound as aiorementioned naturally is a major objective.

Viewed inanother aspect, the invention may be regarded as encompassing a novel method 50 of lubricating bearing metal surfaces, of the character of cadmium-silver, cadmium-nickel, copper-lead, high-lead or like alloys, by applying thereto a film of lubricant comprising mineral hydrocarbon oil having incorporated 55 therewith a small but effective proportion of triphenyl arsine sulfide. lubrication it has been found that prolonged life and consequent improved service may be attained in the use of these alloys as bearing metals of internal combustion engines, particularly when operating conditions such as high sustained speeds under load occasion unusually high bearing surface temperatures. Ordinarily, the oil selected for use, in applying the lubricating method of the invention to its intended service, Will be of a character generally regarded as of superior grade and refining. Thus, the invention finds particular utility in making possible the beneficial use of suchoils by avoiding deleterious consequences otherwise encountered when no preventive measures are taken against the corrosive deterioration of bearing metal alloys'as hereinbefore referred to. It will be understood, however, that the invention contemplates no limitation ln this respect, and that the method of lubrication herein described may be practiced in conjunction with mineral hydrocarbon lubricating oils taken as a broad class and regardless of origin.

Triphenyl arsine sulfide is a compound conforming to the structural formula and may be prepared, for example, by heating triphenyl arsine with sulfur. Solubility in mineral hydrocarbon oil of motor lubricating oil character is limited, but the proportion necessary to accomplish the objects of the present invention is well within the limits of solubility. It suffices, therefore, simply to dissolve t r' phenyl arsine sulfide (if desired with moderate application of heat to facilitate solution) in motor oil intended for service in internal combustion engines in order to prepare for the lubrication thereof according to the invention. Proportions of 0.2% by weight or less of the in hibitor dissolved in motor oilhave proved inhibitive of the corrosion normally attending the use of many lubricating oils with bearing metals of the type comprising cadmium-silver andlike alloys. The stated percentage is not intended as a limitation upon the contemplated scope and practice of the'invention, as obviously the inhibitor may be, and is intended to be, employed in any corrosion inhibiting proportion.

The tendency of motor oils to corrode bearings of the character in question may be determined by a convenient test which affords a ready method of obtaining a comparative evaluation of motor oils in the laboratory. In this test method a group of bearings, ordinarily including at least one each of several of the newer bearing metal alloys (viz: cadmium-silver, cadmium-nickel and copper-lead) is supported in a chamber in which air may circulate and the bearing surfaces are exposed for a period of 22 hours to a stream of oil sprayed under pressure continuously upon the corrodible area. The oil is maintained ata temperature of approximately 335 F. and the spray is so directed as to disperse the oil over the surfaces of the bearings. Means are provided for re-circulating the sprayed oil so that a given quantity is used for With this method of a given test, thus simulating service conditions in an engine. The measure of corrosion is taken as the loss in weight of the bearing per unit of exposed corrodible surface.

The test method described above is carried out in the familiar Underwood corrosion apparatus supplied by the Scientific Instrument Company of Detroit, Michigan, in accordance with General Motors specifications.

Results obtained utilizing the foregoing test for comparative evaluation of motor oils with and without an inhibitor according to the invention providespecific illustration of the value and inhibiting'eifectiveness of triphenyl arsine sulfide. The oil used for the test was an S. A. E. 20 motor oil comprising a. blend of well refined parafllnic base stocks and having an A. P. I. gravity of 30.1, Saybolt viscosity at 100 F. of about 300 seconds, Saybolt viscosity at 210 F. of 54 seconds and flash point of 425. F. Inhibitor, when added, was used in an amount of 0.2% by weight based on the oil. During each run cadmium-silver, cadmium-nickel and copper-lead bearings all were present; and comparative losses in weight per square decimeter due to corrosion were observed as follows for the respective bearings:

O'l t h l l n eny Bearing blan :rsine sulfide Grams Cadmium-silver 7. No loss. Cadmium-nickel. 7. 4 Do. Copper-lead l. 8 Do.

While the utility of the invention has been illustrated specifically with reference to a particular motor oil, no limitation is to be inferred therefrom, and other oils, whether or not comparable in specification or origin, may be used in the lubrication of bearings of the type described in accordance with the invention.

in corrosion inhibiting proportions of triphenyl arsine sulfide.

2. The method of lubricating bearing surfaces in internal combustion engines, which bearing surfaces have substantially the corrosion susceptibility characterizing cadmium-silver, cadmiumnickel and copper-lead alloys, which consists in applying to said bearing surfaces lubricant comprising mineral hydrocarbon oil normally tending to corrode said surfaces and having incorporated therein corrosion inhibiting proportions of triphenyl arsine sulfide.

3. In the lubrication of bearing surfaces having substantially the corrosion susceptibility characterizing cadmium-silver, cadmium-nickel and copper-lead alloys, with mineral hydrocarbon oil normally tending to cause substantial and rapid corrosion thereof, the method of inhibiting such corrosion, which comprises incorporating with said oil corrosion inhibting proportions of triphenyl arsine sulfide.

4. A lubricant for the lubricationof internal combustion engines operating at high sustained speeds and employing bearings presenting bearing surfaces of an alloy selected from the class of cadmi -silver, cadmium-nickel and copperlead alloys, which comprises a well refined mineral lubricating oil of the character normally efiectlve to cause substantial corrosion of such bearing surfaces, and'added triphenyl arsin'e sulfide in corrosion inhibiting proportions.

5. Mineral oil composition, comprising a hydrocarbon lubricating oil of motor oil character normally tending to corrode bearing metals having substantially the corrosion susceptibility characterizing cadmium-silver, cadmium-nickel alloys when continuously apthereoi for an extended and copper-lead plied to the surface at least corrosion inhibiting incorporated with said oil 

